The National Research Council in 2001, recognizing the need for multi-disciplinary research and longitudinal studies on aging, emphasized that cross-national studies can provide substantially more useful evidence for policy than can single country studies. The Council also stressed the need for harmonizing and standardizing data collection across countries. In a more recent publication in 2008, it stressed that including biological indicators in social surveys will ....encourage broader integrative thinking and produce deeper understanding of mechanisms and causal linkages. It is with this intent that WHO's Study on Global Ageing and Adult Health (SAGE) has been designed using a set of methods to provide comparable cross-national data that can be compared to efforts in the US such as the Health and Retirement Study (HRS). The proposed study aims to measure trends in disability (understood as non-fatal health outcomes that capture a state less than full health) in aging cohorts in the World Health Organization (WHO)'s Study on Global Aging and Adult Health (SAGE) across the age range of older adults. It aims to do this by improving the measurement of non-fatal health outcomes, chronic diseases and risk factors in household survey settings and examine the links between non-fatal health outcomes, their determinants such as chronic disease and risk factors and future health outcomes including mortality. It also aims to examine the relationship between economic activity, quality of life, well-being and non-fatal health outcomes in aging populations in low and middle income countries. By improving the measurement of morbidity and tracking respondents over time it will attempt to answer the critical questions related to the future health of ageing populations. Wave 3 data will provide at least 3, and for some respondents 4, data points (SAGE Waves 0-3). The populations covered by participating countries covers over 40% of the world's population aged 60 years and older. Data from the study will have direct implications for understanding the health of older adults in the US, especially those from lower socioeconomic classes and minority populations that are at greatest risk of poor health. The proposed study will make all anonymized micro data available to researchers along with a full documentation of all metadata as per current standards.